Many digital devices have become consumer goods. Digital phones, digital cameras, digital music players, personal digital assistants (PDAs) and personal computers are just some examples of popular digital technology. With the growth of such technology comes a desire to transfer digital information between devices. In the context of portable digital devices, such information transfer becomes particularly desirable.
Portable digital devices often omit many amenities to maximize portability. For example, portable digital devices may lack a full-scale user interface, an ability to store data on archival media, and features having a significant power demand (e.g., advanced digital processing features). Consequently, a desirable feature of any portable digital device is the ability to transfer digital information between the portable digital device and a host digital device having the desired features.
Information transfer may be done directly, or alternatively may be done using information storage media. One information storage medium of particular interest is a solid-state memory device. Such a memory device may be packaged into a removable memory card. The portable digital device may store information on the memory device. The memory device may then be coupled to a host digital device, perhaps after being removed from the portable digital device. The host digital device may then retrieve stored information from the memory device. Of course information transfer may be bidirectional, so the host digital device may store data in the memory device and the portable digital device may retrieve data from the memory device.
Currently, memory cards have a data storage capacity in a range from about 2 megabytes (MB) to about 1 gigabyte (GB) with larger capacities expected in the near future. Although many memory cards provide large volumes of memory, the data transfer rate for retrieving files from memory are often rather slow, i.e., on the order of 10 to 20 MB/sec. At this rate, a host digital device would take nearly 1–2 minute to retrieve 1 GB from a memory card. Thus it would be desirable to have an information transfer protocol offering significantly higher transfer speeds without substantially increased complexity on a memory device.